add basic implementation of ppu write registersHEADmaster

1 files changed, 6 insertions, 6 deletions

diff --git a/ppu.h b/ppu.h
index c5483e1..d7cd93c 100644
--- a/ppu.h
+++ b/ppu.h
@@ -17,11 +17,11 @@ struct ppu {
 	uint8_t last_read;
 
 	struct ppu_regs {
-		uint16_t v : 15; /* current vram address */
-		uint16_t t : 15; /* temporary vram address */
-		uint8_t x : 3;   /* fine x scroll */
-		uint8_t w : 1;   /* first/second write toggle */
-		uint8_t padding : 6;
+		uint16_t v : 15;          /* current vram address */
+		uint16_t t : 15;          /* temporary vram address */
+		uint16_t scroll_x : 9;    /* x scroll position */
+		uint16_t scroll_y : 9;    /* y scroll position */
+		uint8_t write_toggle : 1; /* first/second write toggle */
 	} regs;
 
 	struct ppu_ctrl {	/* $2000 */
@@ -31,7 +31,7 @@ struct ppu {
 		uint8_t bg_tile_sel : 1;
 		uint8_t sprite_tile_sel : 1;
 		uint8_t inc_mode : 1;
-		uint8_t nametable_sel : 2;
+		uint8_t nametable_base : 2;
 	} ctrl;
 	struct ppu_mask {	/* $2001 */
 		uint8_t colour_emphasis : 3;